Darwin’s Planaria elegans: hidden, extinct or misidentified?

by Piter Kehoma Boll

During his epic voyage on the Beagle, Charles Darwin visited Rio de Janeiro, Brazil, and collected some amazing land planarians, a group that until then was very little known. One of the species he found was Geoplana vaginuloides, the type-species of the genus Geoplana, at that time named Planaria vaginuloides.

Geoplana vaginuloides (Darwin, 1844), the first Brazilian land planarian species to be described. Photo by Fernando Carbayo.*

The second species described by Darwin was named Planaria elegans. Darwin’s description is as it follows:

“Position of the orifices as in P. vaginuloides. Anterior part of the body little elongated. Ocelli absent on the anterior extremity, and only a few round the margin of the foot. Colours beautiful; back snow-white, with two approximate lines of reddish brown; near the sides with several very fine parallel lines of the same tint; foot white, exteriorly clouded, together with the margin of the body, with pale blackish purple: body crossed by three colourless rings, in the two posterior of which the orifices are situated. Length 1 inch; breadth more uniform, and greater in proportion to length of the body, than in last species.
Hab. Same as in P. vaginuloides. [Rio de Janeiro]”

And this is all we know about this species. Darwin did not provide any drawing and later researchers did not report this species again, except when mentioning Darwin’s publication. As you can see by the description, it is not very accurate. He does not say what is the breadth of each line or band, neither how many of the “several fine parallel lines of the same tint” there are. Here is a quick drawing I did of how I imagine the creature would be:

My idea of what Darwin’s Planaria elegans may have looked like. Head to the left. Credits to myself, Piter Kehoma Boll.**

In 1938, Albert Riester described a land planarian from Barreira, a district in the city of Teresópolis, Rio de Janeiro, naming it Geoplana barreirana. He described it as it follows (translated from the original in German):

“Land planarian found on a leaf after a rain; greatest lenght ca. 20 mm. Middle of the back white with two fine purple-red (atropurpureus light) parallel stripes. Outside of the white also limitted by pale red, then follows (on both sides) a black band and laterally a black-brown marmorate pattern over brown background. The middle stripe ends at the rear [end]. Head spotted, marked with transversal spotted bands (regenerate?). Underside gray, bordered by black-brown. Anterior end is arched backwards.”

Fortunately, Riester provided a drawing, which you can see below:

Geoplana barreirana drawn by Riester (1938).

They look a bit alike, right? Fortunately Geoplana barreirana (currently named Barreirana barreirana) was found by later researchers and we have photographs! See one specimen below:

A specimen of Barreirana barreirana found in the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

Riester did not describe any transversal marks on his specimens, but he may have mistaken them for color loss in preserved specimens or something like that. Otherwise the specimen looks very similar to Riester’s drawing, and the internal anatomy, which Riester provided as well, is also compatible.

Now let’s try to fit Darwin’s description of Planaria elegans in this photograph. White background, two reddish brown stripes and several fine parallel stripes of the same tint. He likely described the animals from preserved specimens, even though he have seen them alive and collected them. Perhaps the colors had already faded a little and the black stripes, which internally touch two of the reddish stripes, may have been considered a single purple-red stripe? It is not clear, in his description, whether there is white between the “reddish brown” stripes and the “pale blackish-purple” sides, as I did in my drawing, or not, as in Barreirana barreirana, but certainly the dark gray sides of B. barreirana could be the same as the pale blackish purple sides of Planaria elegans, don’t you think? And B. barreirana HAS three white “rings” crossing the body. You can see the first and the second very clearly on the specimen above. The third one is not very well marked, but you can see a third white mark interrupting the gray sides. And the second and almost third marks seem to be quite where one would expect the two orifices (mouth and gonopore) of the planarian to be!

And what about the ventral side? Darwin described P. elegan‘s as being white with a pale blackish purple border as the sides of the dorsum. Riester described G. barreirana‘s as being gray bordered by black-brown. Here is Barreirana barreirana‘s ventral side:

Ventral side of Barreirana barreirana from the Tijuca National Park, Rio de Janeiro. Photo by Fernando Carbayo.*

It is white, or pale gray perhaps, and the borders are of the same color as the sides of the dorsum!

I think it is very, very likely that Darwin’s Planaria elegans and Riester’s Geoplana barreirana are the same species. The fact that no one but Darwin has ever seen a specimen of Planaria elegans makes it even more likely.

What do you think?

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See also:

How are little flatworms colored? A Geoplana vaginuloides analysis.

The fabulous taxonomic adventure of the genus Geoplana.

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References:

Darwin, C. (1844) Brief Description of several Terrestrial Planariae, and of some remarkable Marine Species, with an Account of their Habits. Annals and Magazine of Natural History 14, 241–251.

Riester, A. (1938) Beiträge zur Geoplaniden-Fauna Brasiliens. Abhandlungen der senkenbergischen naturforschenden Gesellschaft 441, 1–88.

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*
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

**
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Furia infernalis, a legendary parasite

by Piter Kehoma Boll

The year was 1728. The young naturalist Carl Linnaeus was exploring some marshes in the vicinities of Lund, Sweden, in search of botanical specimens. Suddenly he was wounded by something that felt like a sudden dart hitting the skin. Linnaeus deduced that the cause was a small slender worm that buried itself deeply and quickly in the flesh, so that it was impossible to try to extract it. The wound caused such a severe inflammation that his life became endangered. He recovered, of course, but was so deeply impressed by the experience that he gave a name to the supposed animal, Furia infernalis, the fury from Hell, and introduced it in his famous Systema Naturae.

Several naturalists continued to spread the idea of such an animal and several works regarding the creature were published by very respected cientists. The animal was described as being a greyish worm of the thickness of a hair and with black extremities that inhabits marshy places and darts itself upon the exposed parts of the bodies of humans and other animals that happen to be in its reach. The torments caused by the worm after quickly burying itself in the flesh were so excruciating that they throw the victim into a state of madness and wild rage.

The Furia infernalis was supposed to look somewhat like this.

The idea of the existence of the creature soon became settled in people’s minds. The animal was supposed to live only in eastern Scandinavia and perhaps Russia and the Baltic contries, but did not happen further to the south nor in Norway. Even some medical treatments to cure the infection were published.

An older, wiser and more experienced Linnaeus, many years later, altered his opinion on the creature. He admitted that he possibly was drawn into error regarding the creature’s nature or even existence and considered it to be entirely fictional. However, it was too late. New cases of attacks continued to appear and the worm seemed to be a special danger to reindeer. Accounts regarding entire herds of reindeer being killed by the creature were so frequent that the purchase of animals from Sweden was entirely forbidden during the periods in which the disease was frequently reported.

Despite all the alarm, no one ever was able to present a specimen of the creature in order to validate its existence. The problem with the deer were later discovered to be caused by cestode larvae in the brain, i.e., they were afflicted by neurocysticercosis.

Today Furia infernalis is considered to be an entirely fictional animal belonging to the realm of Cryptozoology. But I wonder what had stung Linnaeus in that marsh three centuries ago.

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References:

Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae…

Brooke, A. C. 1827. On the Furia infernalis. Edinburgh New Philosophical Journal, 3: 39-43.

What on Earth is Leimacopsis terricola? A flatworm mystery.

by Piter Kehoma Boll

Oh, ye olde times…

The 18th and 19th centuries were well marked by great worldwide expeditions by naturalists aboard ships travelling all around the world. Charles Darwin is certainly the most famous of them, but he was not the only one.

One of those naturalists was Karl Ludwig Schmarda, born in 1819. He studied in Vienna and was later a professor at the University of Graz, Austria. From 1853 to 1857, he travelled around the world investigating several locations and collecting primarily invertebrates. After his return, he published a work entitled Neue wirbellose Thiere beobachtet und gesammelt auf einer Reise um die Erde 1853 bis 1857 (New invertebrate animals observed and sampled on a travel around the Earth, 1853 to 1857).

Among the countless animals that he described, there was a worm which he called Prostheceraeus terricola. The description is as it follows:

Prostheceraeus terricola. Schmarda.
Taf. VI. Fig. 69.

Char. : Corpus oblongo-lanceolatum. Dorsum convexum viride. Fascia mediana et margo purpureus. Tentacula subuliformia.

Der Körper ist weniger flach als in andern Planarien, länglich, hinten lanzettförmig zugespitzt, vorne beinahe quer abgeschnitten. Die Fühler sind kurz und pfriemenförmig zugespitzt. Der Rücken ist stark convex, fast grasgrün, mit einer purpurrothen Längslinie nach seinem ganzen Verlaufe. Der Rand nicht wellenförmig, purpurroth gesäumt. Die Hauchfläche ist grünlichgrau. Die Länge 20mm, grösste Breite 5mm. Die Augen sind am innern Rande und der Basis der Fühler. Die Gruppe im Nacken, habe ich nicht beobachtet. Die Mundöffnung ist im vordern Drittel. Die Geschlechtsöffnungen habe ich nicht aufgefunden.
Der Grund meiner unvollständigen Kenntniss dieser Thierform ist der Umstand, dass ich nur ein Exemplar in dem obern Theile des Quindiu-Passes ober der Region der Bergpalmen gefunden hatte, welches ich in Gallego skizzirte, das aber schon zu Grunde gegangen war, als ich es in meiner Abendstation in Tocho einer wiederholten nähern Prüfung unterziehen wollte.

In English:

Oblong-lanceolate body. Green convex dorsum. Median and marginal purple stripes. Awl-like tentacles.

The body is less flat than in other planarians, elongated, behind pointed and lanceolate, front almost transversally cut. The feelers are short and awl-like pointed. The back is strongly convex, almost grass green with a purple line running fully along it. Margin not wave-like and purple-colored. The ventral surface is greenish gray. Length 20mm, largest width 5mm. The eyes are at the inner border and the base of the feelers. The group at the neck I didn’t observed. The mouth opening is in the front third. The sexual opening I did not found.
The reason of my incomplete knowledge of this animal form is due to the circumstance of finding only one specimen in the top part of the Quindiu passage above the region of the mountain palms, which I sketched it in Gallego, since it was already deteriorating, to undergo a revision back at the station in Tocho.

Here you can see the drawing of the animal:

Drawing of Prostheceraeus terricola by Schmarda, 1859

Schmarda put other worms in the same genus, all of them marine. The genus is valid until today for marine species and they are classified as belonging to the Polycladida, those beautiful sea flatworms.

In fact, this animal actually looks kind of similar to a polyclad, but Schmarda found it on the top of the mountains! Quite unusual, and unfortunately he found only one single specimen.

Prostheceraeus giesbrechtii, another species described by Schmarda (1859). Photo by Parent Géry taken from commons.wikimedia.org

Later, in 1862, K. M. Diesing made a revision of turbellarians and defined that, as the creature lived on land, it was certainly something other than a polyclad and changed it to a new genus which he called Leimacopsis (slug-like):

XVIII. LEIMACOPSIS DIESING.
Prostheceraei spec. Schmarda.

Corpus elongato-lanceolatum, supra convexum. Caput corpore continuum antice truncatum, tentaculis duobus genuinis frontalibus. Ocelli numerosi tentaculorum. Os ventrale antrorsum situm, oesophago… Apertura genitalis. . . Terrestres, Americae tropicae.

1. Leimacopsis terricola DIESING.
Corpus elongato-lanceolatum, supra convexum, viride, vitta mediana corpori aequilonga et marginibus haud undulatis purpureis, subtus viridi-cinereum. Tentacula subuliformia, brevia. Ocelli ad marginem internum et ad basim tentaculorum. Os in anteriore corporis tertia parte. Longit. 10′”, latit. 2 1/3 “.
Prostheceraeus terricola Schmarda: Neue wirbell. Th. I. 1. 30. Tab. VI. 69.
Habitaculum. In parte superiore transitus Andium Quindiu, supra regionem Palmarum montanarum (Bergpalmen), specimen unicum (Schmarda).

It’s basically a repetition of Schmarda’s description and based only on it. It looks that no other specimens were found until this time.

Years later, in 1877, H. N. Moseley published a catalogue of all land planarians known at the time. He included Leimacopsis terricola with the following description:

Family. — Leimacopsidæ, Diesing.

Genus Leimacopsis. — Diesing, Revision der Turbellarien, Abtheilung Dendrocoelen, Sitzbt. Akad. Wiss., Wien, 1861, p. 488.
Leimacopsis terricola.—Diesing, 1. c.
Prostheraceus terricola. — Schmarda, ‘Neue Wirbellose Thiere,’ Th. 1, 1—30, Tab. VI, fig. 69.
With a pair of true frontal tentacles beset with numerous eyes. Occurs high up in the Andes at the pass of Quindiu, above the region of mountain palms.

As you can see, it’s again simply a repetition of Schmarda’s description based on that single specimen from 20 years earlier, but from Diesing on, the animal started to be considered a land planarian rather than a polyclad.

Now in 1899, Ludwig von Graff published his great monography about turbellarians and I’m certain that I saw something about Leimacopsis there. Unfortunately I never found a digital copy of it and I don’t have a physical copy easily accessible either, but according to Ogren (1992), it has only a repetition of Schmarda’s account. Graff, however, changed the spelling to Limacopsis, but this is not valid according to the International Code of Zoological Nomenclature.

In 1914, finally a new article, by O. Fuhrmann, was published with information about land planarians from Colombia. He begins commenting that there were only three species known for the country by that time, one of them being Limacopsis [sic] terricola. However, the species was not found again this time…

The years passed and nothing changed. In 1991, Ogren and Kawakatsu, in part of their index to the species of land planarians, comment that several researchers, like E. M. Froehlich and L. H. Hyman, considered Leimacopsis terricola as possibly being a slug.

In 1992, Robert Ogren wrote an excellent revision of this species, which presents all information I have given here and much more. He concluded that the organism is a species inquerenda (needing further investigation) and nomen dubium (doubtful name). It is not possible to assign the animal as either a flatworm or a mollusk, or anything else due to the lack of information. Ogren considered it as “clearly part of the lore of Cryptozoology”.

As we can see, cryptids don’t need to be big animals like dinosaurs or big feet. Even a small slug-like worm from the Andes may fit.

Leimacopsis terricola is certainly an interesting organism. What was it really? Was it real? Maybe an extensive research in the area would reveal something… or not. Let’s wait and hope… Or perhaps… what about going to an adventure in Colombia’s Andean region in search of the mysterious creature?

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References:

Diesing, K. M. 1862. Revision der Turbellarien. Abtheilung: Dendrocoelen. Keiserlich-Königlichen Hof- und Staatsdruckerei DOI: 10.5962/bhl.title.2108

Fuhrmann, O. 1914. Planaires terrestres de Colombie. In: Fuhrmann & Mayor (eds.) Voyage d’Exploration Scientifique en Colombie. Mémoires de la Société des sciences naturelles de Neuchâtel, 5 (2), 748-792

Moseley, H. 1874. On the Anatomy and Histology of the Land-Planarians of Ceylon, with Some Account of Their Habits, and a Description of Two New Species, and with Notes on the Anatomy of Some European Aquatic Species. Philosophical Transactions of the Royal Society of London, 164, 105-171 DOI: 10.1098/rstl.1874.0005

Ogren, R. E. 1992. The systematic position of the cryptic land organism, Leimacopsis terricola (Schmarda, 1859)(olim Prostheceraeus)(Platyhelminthes). Journal of The Pennsylvania Academy of Science, 66 (3), 128-134

Ogren, R. E. & Kawakatsu, M. 1991. Index to the species of the family Geoplanidae (Turbellaria, Tricladida, Terricola) Part II: Caenoplaninae and Pelmatoplaninae. Bulletin of Fuji Women’s College, 29, 35-58

Schmarda, L. K. 1859. Thiere beobachtet und gesammelt auf einer Reise um die Erde 1853 bis 1857. Lepizig: W. Engelmann. DOI: 10.5962/bhl.title.14426